1. Field of the Invention
The present invention relates to a multi-point driving device for general-purpose base station antenna, and in particular to an electronic scale that features automatic cable retraction and is applicable to weighing of an object.
2. The Related Arts
Conventional directional base station antennas have been widely used in mobile communication systems. For example, an antenna of base station is used in a mobile phone communication system to effect transmission of signal and to realize an effective transmission of signal through a conventional directional antenna, variation of the azimuth angle and tilt angle of the antenna must be properly controlled. A conventional driving mechanism that is used to vary azimuth angle and tilt angle of a base station antenna is generally classified as two groups, of which one comprises installation of driving components, such as linkage or worm and motor, inside a base station antenna for driving the antenna to vary the azimuth or tilt angle. However, such an arrangement must install complicated driving components, such as linkage or worm and motor, in an interior space of the base station antenna and this complicates the structure of the base station antenna, making the manufacture and maintenance of the base station antenna difficult and also making the manufacture cost of the base station antenna excessively high. Further, the exterior of the base station antenna must be fixed by applying an additional fixture and this takes another expense of installation of the base station antenna.
Another know driving mechanism for varying azimuth angle of base station antenna takes the form of single-point single-direction rotary driving mechanism, as well as associated method, that is mounted at a bottom end or a central section of the exterior of the base station antenna. For example, when the base station antenna is rotated to vary azimuth angle, it is not possible to simultaneously vary the azimuth angle and the tilt angle of the base station antenna, whereby a driving mechanism must be additionally arranged inside the base station antenna to effect driving and varying of the antenna tilt angle. The same problem and drawback as the previously discussed arrangement of installing tilt angle driving mechanism in the interior of the base station antenna is applicable here again. Further, the base station antenna, which is usually disposed outdoors, must be resistive to interference caused by loading of wind power. In addition, the rotary driving mechanism is arranged at the bottom of the base station antenna, and it is necessary to bypass control cables and power cables connected to the bottom of the base station antenna. Further, such control cables and power cables may be uncontrollably cause twisting or entangling problem at the bottom of the base station antenna during the rotation of the base station antenna.
Known references include for example Taiwan Patent Publication No. 538557, which discloses an invention relating to honeycomb base station antenna, Taiwan Patent Publication No. 320786, which discloses a driving device that adjusts a plurality of phase shifters to induce relative phase shifting, an antenna system, and a communication system, Chinese Patent Publication No. CN102122758, which discloses a base station antenna capable of electrically adjusting electric downward inclination and a control method thereof, US Patent Publication No. 2009/0135074, which relates to a “single drive variable azimuth and beam tilt antenna for wireless network”, US Patent Publication No. 2010/0201590, which relates to a “remote electrical tilt antenna with motor and clutch assembly”, and U.S. Pat. No. 7,015,871, which relates to a “mobile radio antenna arrangement for a base station”. All these prior art references disclose the typical known techniques that arrange tilt angle or azimuth angle driving mechanism in the interior of a base station antenna. And, similar to the previously discussed conventional base station antennas, these prior art references share the same problems and drawbacks of being difficult to manufacture and maintain, excessively high costs, and requiring additionally mounted fixtures outside the base station antenna that are caused by arranging the driving mechanism for controlling azimuth angle or tilt angle in the interior thereof.
Further, Taiwan Patent Publication No. 253917, which relates to an antenna direction adjusting device for mobile phone base station, and Taiwan Utility Model No. M398208, which relates to a universal horizontal rotation unit for directional antenna, both disclose effecting rotation of azimuth angle through single-point driving, and thus rotating, of the base station antenna that is performed at a bottom end or central section of the exterior of a base station antenna. Again, the same problems and drawbacks of single-point driving at the bottom end and central section of the exterior of the base station antenna being incapable of simultaneously varying the tilt angle, insufficient capability of resisting interference caused by loading of wind power, and being necessary to bypass the control cables and the power cables arranged at the bottom of the base station antenna in order to eliminate entangling of cables, which are found in the previously discussed antenna